Quality control of translation on the ribosome

点击翻译按钮获取中文摘要

The scope of the present proposal is to acquire quantitative understanding of quality control mechanisms of translation initiation and elongation in bacteria. Kinetic mechanisms of both reactions will be studied, monitoring fluorescence signals, including FRET, of labels introduced into components of the translation machinery. Control steps in translation initiation will be identified, and the mechanisms by which the differences in the translation initiation region of mRNAs are recognized by the initiation machinery will be investigated. Another aim is to understand the high fidelity of protein synthesis during elongation using a systems-biology approach. The kinetics of reactions that govern acceptance or rejection of aminacyl-tRNA (aa-tRNA) substrates will be measured on cognate and near-cognate codons in the absence and presence of competitor aa-tRNA. A mathematical competition model will be built to make testable predictions as to how the fidelity of protein synthesis changes with the physiological state of the cell. Finally, we plan to study the mechanism of programmed -1 frameshifting. The timing of ribosome pausing and the step at which frameshifting takes place will be determined. We will test whether one or two tRNAs are involved in frameshifting, and whether EF-G has to be present on the ribosome during slippage.